Battery tester for electric vehicle

ABSTRACT

Testing or diagnostics are performed on an electric vehicle. The vehicle is operated and current flow through a system of the vehicle is monitored. A voltage related to the system is also monitored. Diagnostics are provided based upon the monitored voltage and the monitored current.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a Continuation-In-Part of Ser. No. 12/174,894, filed Jul. 17, 2008, which is based on and claims the benefit of U.S. provisional patent application Ser. No. 60/950,182, filed Jul. 17, 2007, and U.S. provisional patent application Ser. No. 60/970,319, filed Sep. 6, 2007, the contents of which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to test equipment for electric vehicles. More specifically, the present invention relates to a tester for testing electrical systems of an electric vehicle.

Various types of electronic battery tester are known in the art. Electronic battery techniques have been pioneered by Midtronics, Inc. of Willowbrook, Ill. and Dr. Keith S. Champlin. Examples are shown and described in U.S. Pat. No. 3,873,911, issued Mar. 25, 1975, to Champlin; U.S. Pat. No. 3,909,708, issued Sep. 30, 1975, to Champlin; U.S. Pat. No. 4,816,768, issued Mar. 28, 1989, to Champlin; U.S. Pat. No. 4,825,170, issued Apr. 25, 1989, to Champlin; U.S. Pat. No. 4,881,038, issued Nov. 14, 1989, to Champlin; U.S. Pat. No. 4,912,416, issued Mar. 27, 1990, to Champlin; U.S. Pat. No. 5,140,269, issued Aug. 18, 1992, to Champlin; U.S. Pat. No. 5,343,380, issued Aug. 30, 1994; U.S. Pat. No. 5,572,136, issued Nov. 5, 1996; U.S. Pat. No. 5,574,355, issued Nov. 12, 1996; U.S. Pat. No. 5,583,416, issued Dec. 10, 1996; U.S. Pat. No. 5,585,728, issued Dec. 17, 1996; U.S. Pat. No. 5,589,757, issued Dec. 31, 1996; U.S. Pat. No. 5,592,093, issued Jan. 7, 1997; U.S. Pat. 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No. 09/780,146, filed Feb. 9, 2001, entitled STORAGE BATTERY WITH INTEGRAL BATTERY TESTER; U.S. Ser. No. 09/756,638, filed Jan. 8, 2001, entitled METHOD AND APPARATUS FOR DETERMINING BATTERY PROPERTIES FROM COMPLEX IMPEDANCE/ADMITTANCE; U.S. Ser. No. 09/862,783, filed May 21, 2001, entitled METHOD AND APPARATUS FOR TESTING CELLS AND BATTERIES EMBEDDED IN SERIES/PARALLEL SYSTEMS; U.S. Ser. No. 09/880,473, filed Jun. 13, 2001; entitled BATTERY TEST MODULE; U.S. Ser. No. 10/042,451, filed Jan. 8, 2002, entitled BATTERY CHARGE CONTROL DEVICE; U.S. Ser. No. 10/109,734, filed Mar. 28, 2002, entitled APPARATUS AND METHOD FOR COUNTERACTING SELF DISCHARGE IN A STORAGE BATTERY; U.S. Ser. No. 10/112,998, filed Mar. 29, 2002, entitled BATTERY TESTER WITH BATTERY REPLACEMENT OUTPUT; U.S. Ser. No. 10/263,473, filed Oct. 2, 2002, entitled ELECTRONIC BATTERY TESTER WITH RELATIVE TEST OUTPUT; U.S. Ser. No. 10/310,385, filed Dec. 5, 2002, entitled BATTERY TEST MODULE; U.S. Ser. No. 10/653,342, filed Sep. 2, 2003, entitled ELECTRONIC BATTERY TESTER CONFIGURED TO PREDICT A LOAD TEST RESULT; U.S. Ser. No. 09/653,963, filed Sep. 1, 2000, entitled SYSTEM AND METHOD FOR CONTROLLING POWER GENERATION AND STORAGE; U.S. Ser. No. 10/174,110, filed Jun. 18, 2002, entitled DAYTIME RUNNING LIGHT CONTROL USING AN INTELLIGENT POWER MANAGEMENT SYSTEM; U.S. Ser. No. 10/258,441, filed Apr. 9, 2003, entitled CURRENT MEASURING CIRCUIT SUITED FOR BATTERIES; U.S. Ser. No. 10/681,666, filed Oct. 8, 2003, entitled ELECTRONIC BATTERY TESTER WITH PROBE LIGHT; U.S. Ser. No. 10/791,141, filed Mar. 2, 2004, entitled METHOD AND APPARATUS FOR AUDITING A BATTERY TEST; U.S. Ser. No. 10/867,385, filed Jun. 14, 2004, entitled ENERGY MANAGEMENT SYSTEM FOR AUTOMOTIVE VEHICLE; U.S. Ser. No. 10/958,812, filed Oct. 5, 2004, entitled SCAN TOOL FOR ELECTRONIC BATTERY TESTER; U.S. Ser. No. 60/587,232, filed Dec. 14, 2004, entitled CELLTRON ULTRA, U.S. Ser. No. 11/018,785, filed Dec. 21, 2004, entitled WIRELESS BATTERY MONITOR; U.S. Ser. No. 60/653,537, filed Feb. 16, 2005, entitled CUSTOMER MANAGED WARRANTY CODE; U.S. Ser. No. 60/665,070, filed Mar. 24, 2005, entitled OHMMETER PROTECTION CIRCUIT; U.S. Ser. No. 60,694,199, filed Jun. 27, 2005, entitled GEL BATTERY CONDUCTANCE COMPENSATION; U.S. Ser. No. 11/178,550, filed Jul. 11, 2005, entitled WIRELESS BATTERY TESTER/CHARGER; U.S. Ser. No. 60/705,389, filed Aug. 4, 2005, entitled PORTABLE TOOL THEFT PREVENTION SYSTEM, U.S. Ser. No. 11/207,419, filed Aug. 19, 2005, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION FOR USE DURING BATTERY TESTER/CHARGING, U.S. Ser. No. 60/712,322, filed Aug. 29, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE, U.S. Ser. No. 60/713,168, filed Aug. 31, 2005, entitled LOAD TESTER SIMULATION WITH DISCHARGE COMPENSATION, U.S. Ser. No. 60/731,881, filed Oct. 31, 2005, entitled PLUG-IN FEATURES FOR BATTERY TESTERS; U.S. Ser. No. 60/731,887, filed Oct. 31, 2005, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER THAT CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/304,004, filed Dec. 14, 2005, entitled BATTERY TESTER WITH CALCULATES ITS OWN REFERENCE VALUES; U.S. Ser. No. 60/751,853, filed Dec. 20, 2005, entitled BATTERY MONITORING SYSTEM; U.S. Ser. No. 11/356,443, filed Feb. 16, 2006, entitled ELECTRONIC BATTERY TESTER WITH NETWORK COMMUNICATION; U.S. Ser. No. 11/498,703, filed Aug. 3, 2006, entitled THEFT PREVENTION DEVICE FOR AUTOMOTIVE VEHICLE SERVICE CENTERS; U.S. Ser. No. 11/511,872, filed Aug. 29, 2006, entitled AUTOMOTIVE VEHICLE ELECTRICAL SYSTEM DIAGNOSTIC DEVICE; U.S. Ser. No. 11/519,481, filed Sep. 12, 2006, entitled BROAD-BAND LOW-CONDUCTANCE CABLES FOR MAKING KELVIN CONNECTIONS TO ELECTROCHEMICAL CELLS AND BATTERIES; U.S. Ser. No. 60/847,064, filed Sep. 25, 2006, entitled STATIONARY BATTERY MONITORING ALGORITHMS; U.S. Ser. No. 11/641,594, filed Dec. 19, 2006, entitled METHOD AND APPARATUS FOR MEASURING A PARAMETER OF A VEHICLE ELECTRONIC SYSTEM; U.S. Ser. No. 11/711,356, filed Feb. 27, 2007, entitled BATTERY TESTER WITH PROMOTION FEATURE; U.S. Ser. No. 11/811,528, filed Jun. 11, 2007, entitled ALTERNATOR TESTER; U.S. Ser. No. 60/950,182, filed Jul. 17, 2007, entitled BATTERY TESTER FOR HYBRID VEHICLE; U.S. Ser. No. 60/973,879, filed Sep. 20, 2007, entitled ELECTRONIC BATTERY TESTER FOR TESTING STATIONARY BATTERIES; U.S. Ser. No. 11/931,907, filed Oct. 31, 2007, entitled BATTERY MAINTENANCE WITH PROBE LIGHT; U.S. Ser. No. 60/992,798, filed Dec. 6, 2007, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 12/099,826, filed Apr. 9, 2008, entitled BATTERY RUN DOWN INDICATOR; U.S. Ser. No. 61/061,848, filed Jun. 16, 2008, entitled KELVIN CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/168,264, filed Jul. 7, 2008, entitled BATTERY TESTERS WITH SECONDARY FUNCTIONALITY; U.S. Ser. No. 12/174,894, filed Jul. 17, 2008, entitled BATTERY TESTER FOR ELECTRIC VEHICLE; U.S. Ser. No. 12/204,141, filed Sep. 4, 2008, entitled ELECTRONIC BATTERY TESTER OR CHARGER WITH DATABUS CONNECTION; U.S. Ser. No. 12/328,022, filed Dec. 4, 2008, entitled STORAGE BATTERY AND BATTERY TESTER; U.S. Ser. No. 12/416,457, filed Apr. 1, 2009, entitled SYSTEM FOR AUTOMATICALLY GATHERING BATTERY INFORMATION; U.S. Ser. No. 12/416,453, filed Apr. 1, 2009, entitled INTEGRATED TAG READER AND ENVIRONMENT SENSOR; U.S. Ser. No. 12/416,445, filed Apr. 1, 2009, entitled SIMPLIFICATION OF INVENTORY MANAGEMENT; U.S. Ser. No. 12/485,459, filed Jun. 16, 2009, entitled CLAMP FOR ELECTRONICALLY COUPLING TO A BATTERY CONTACT; U.S. Ser. No. 12/498,642, filed Jul. 7, 2009, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/697,485, filed Feb. 1, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/698,375, filed Feb. 2, 2010, entitled ELECTRONIC BATTERY TESTER; U.S. Ser. No. 12/712,456, filed Feb. 25, 2010, entitled METHOD AND APPARATUS FOR DETECTING CELL DETERIORATION IN AN ELECTROCHEMICAL CELL OR BATTERY; U.S. Ser. No. 61/311,485, filed Mar. 8, 2010, entitled BATTERY TESTER WITH DATABUS FOR COMMUNICATING WITH VEHICLE ELECTRICAL SYSTEM U.S. Ser. No. 61/313,893, filed Mar. 15, 2010, entitled USE OF BATTERY MANUFACTURE/SELL DATE IN DIAGNOSIS AND RECOVERY OF DISCHARGED BATTERIES; which are incorporated herein in their entirety.

Many electric vehicles use a storage battery pack or other electrical storage device, to store energy for use in operating the electric vehicle. Some such electric vehicles use energy recovery (or “regeneration”) techniques in which potentially waste energy is recovered and stored in the energy storage device. One example is recovery of energy from braking function. The energy in braking is recovered as electrical energy rather than being dissipated as excess heat. Preferably, the energy storage device is able to efficiently store the excess energy, as well as deliver energy to an electrical motor of the electric vehicle. Due to the increasing price of petroleum, hybrid systems are rapidly proliferating. There is an ongoing need to test the electrical systems of such electric vehicles.

SUMMARY OF THE INVENTION

Testing or diagnostics are performed on an electric vehicle. The vehicle is operated and current flow through a system of the vehicle is monitored. A voltage related to the system is also monitored. Diagnostics are provided based upon the monitored voltage and the monitored current.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram showing a battery tester in accordance with the present invention coupled to a electric vehicle.

FIG. 2 is a simplified block diagram showing steps in accordance with the present invention.

FIG. 3 is a simplified block diagram which illustrates a test device in accordance with the present invention.

FIG. 4 is a simplified block diagram showing one aspect of the present invention in which the test device couples to the databus of the electric vehicle.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Electric vehicles and hybrid vehicles are becoming increasingly popular as an alternative to traditional vehicles which are powered solely by an internal combustion engine. In a electric vehicle, a large battery or a group of batteries, or other energy storage device, is used to store electrical energy. The stored electrical power is used by an electric motor to power the electric vehicle.

In order to increase energy efficiency, some electric vehicles use various techniques to capture or otherwise recover waste energy. This may be referred to as “regeneration”. The recovered energy is typically returned in the battery of the electric vehicle for storage and subsequent use.

Various techniques are used to recover energy. For example, one common technique is to use the braking system of the electric vehicle to convert vehicle motion into electricity for storage in the battery. This differs from a conventional braking system in which excess energy is vented into the atmosphere as heat.

As the battery of the electric vehicle ages, its ability to store energy also degrades. However, this may not be apparent to the operator, particularly in a hybrid vehicle. One symptom of a failing battery is decreased mileage of the electric vehicle because the battery is not able to effectively store or deliver energy. The health of a battery in a electric vehicle is an indication of how well the battery accepts a charge and is able to deliver stored energy at high discharge rates. To some extent, this relates to the amp hour capacity of the battery as well as the ability of the battery to accept or deliver charge in a given time. This is related to how much recovered energy can be stored at one time for use at a later time. For example, is the battery capable of storing energy from many braking cycles for subsequent use, or is it only able to store energy from a few such braking cycles.

Typical battery testing techniques are difficult to implement in such a electric vehicle. For example, it may be difficult or impossible to access the individual batteries of a battery pack for testing. Such access may require a great deal of labor. Further, there may be safety concerns related to the relatively high voltages involved if the battery pack is disassembled for testing.

With the present invention, a current sensor is coupled to the battery pack of a electric vehicle of the type which includes an electric motor to move the electric vehicle. The current sensor can be placed in line with the battery pack and arranged to measure current into and out of the pack. The total string voltage of the battery pack is also measured. A technician or other service personnel performs a battery test by operating the electric vehicle through a number of braking and acceleration cycles. Data is collected and compared to baseline or nominal data which is representative of operation of a new electric vehicle. An output can be provided based upon the comparison. For example, the output can be an indication of how well the electric vehicle compares to new electric vehicle, for example as a percentage.

The current sensor can be placed in series with one of the battery terminals using a shunt resistance or the like. Another example is a Hall effect or other non-intrusive sensor. Such a sensor is advantageous because it does not require the battery to be disconnected. In another example, an adapter can be configured which can be inserted between the battery pack and the electric vehicle such that the test device can be coupled to the battery.

The various sensors can be coupled at any convenient location, for example, proximate the battery pack, under the hood, near the electric vehicle motor or other electronics. In such an application, a Hall effect sensor may be sufficient because of the relatively large magnitudes of the current levels being monitored. Further, a Hall effect sensor may be easily “zeroed” because during installation there will be no current flowing. Voltage measurements may be made using direct attachment, for example, to the high voltage pole of the battery. The voltage and current measurements may also be obtained through other techniques, for example, through an OBDII interface used to read electrical parameters from the electric vehicle computer system.

During testing, the test device can provide instructions to an operator as to how to operate the electric vehicle. Such instructions can be provided, for example, through a wireless communication link to a device proximate the operator, through a PDA-type device, through audible instructions, through a display of the vehicle, or through other techniques.

If the testing device couples to the OBDII system of the electric vehicle, additional information can be retrieved. For example, information related to the speed (RPM) of a motor, speed of the electric vehicle, braking information, etc. can be recovered. With this additional information, the test device may be used to verify that the technician has performed the required operations. Such operations should have some flexibility in order to reflect safe driving conditions.

FIG. 1 is a simplified block diagram 10 of a electric vehicle 12 coupled to a test device 14. The test device is shown as locate separate from the electric vehicle 12 and may be a portable or stationary device. However, in some configurations the test device 14 may be included in electric vehicle 12. Electric vehicle 12 is illustrated as including battery pack 20, electric motor 22 and energy recovery device 24. As discussed, the battery pack 20 is used to power the electric motor 22 while the energy recover device 24 is used to recover energy during electric vehicle operation. Test circuitry 14 couples to battery 20 and includes or is coupled to voltage sensor 30, memory 32 and microprocessor 33. Further, test circuitry 14 includes or is coupled to a current sensor 34 arranged to sensor current into and/or out of battery pack 20. Test circuitry 14 provides an output through input/output (I/O) 35 as discussed above related to the condition of the battery pack 20. The test circuitry 14 includes a microprocessor 33 or the like which may include either internal or external analog to digital converters configured to convert the sensed voltage current levels to digital values. Microprocessor 33 operates in accordance with instructions stored in memory and provide an output 35 which is related to the condition of the battery pack 20. FIG. 1 also shows an optional internal combustion engine 40 which is used to supplement the energy delivered by battery pack 20. The optional engine 40 can be used to charge battery pack 20, and/or can be used to supplement the electrical power available to motor 22 during times of high acceleration or the like. Thus, engine 40 may include an electric generator 41. Similarly, engine 40 can be configured to provide power directly to wheels or other components of the vehicle 12. The connection of test device 14 to the vehicle 12 may be through an electrical connection to sensors such as the voltage sensor 30 and the current sensor 34. Additionally, the voltage sensor 30 and current sensor 34 can comprise components within the vehicle 12. In such a configuration, test device 14 can couple to the vehicle through a data connection to the vehicle, for example, an OBDII connection to the vehicle in which current and voltage information are read back from the vehicle. For example, the data can be recovered as it is transmitted on the vehicle databus or the data can be retrieved by placing commands on the databus to access the desired information.

FIG. 2 is a simplified block diagram showing steps in accordance with one example embodiment of the present invention. The block diagram of FIG. 2 begins at start block 50 and controls past block 52 where the electric vehicle is operated and data is collected. At block 54, nominal data is recovered. For example, such nominal data can be stored in memory 32 shown in FIG. 1. The nominal data can be related to a baseline condition, for example, the condition of the battery pack and/or in electric vehicle 12 when they are new. At block 56, the collected data is compared to the nominal data and an output is provided at block 58. The output can be, for example, a relative output with respect to the current condition of electric vehicle in battery relative to a new electric vehicle or battery. This may be in the form of, for example, a percentage or other format. At block 60, the process is terminated.

FIG. 3 is a simplified block diagram showing test device 14 in greater detail. Test device 14 is illustrated as including differential amplifier 102 which couples to current sensor 34. A second differential amplifier 98 couples to battery 20 and forms the voltage sensor 30. The voltage sensor 30 may be a part of, or may be separated from, the test device 14. The output from the amplifier 98 is provided to an analog to digital converter 100 which couples microprocessor 33. Similarly, the output of amplifier 102 is converted into a digital format for microprocessor 33 using analog to digital converter 104. The actual voltage and current sensors may be in accordance with any technique and are not limited to the techniques described herein. As discussed below, the current and voltage sensors may be a part of vehicle 12 and the test can retrieve their information over a databus of the vehicle.

Microprocessor 33 operates in accordance with instructions stored in memory 32 and is configured to communicate with an operator through user input/output (I/O) 110. An optional OBDII interface, as illustrated at OBDII I/O 112, is provided. OBDII I/O 112 is configured to couple to the OBDII databus of the electric vehicle 12. The user I/O 110 can be any type of user input and output including, for example, a button or keypad entry, a display including a graphical display, an audio output including voice prompts, or other input or output techniques.

FIG. 4 is a simplified block diagram showing another aspect of the present invention. As discussed above, test device 14 couples to the on board databus 130 of electric vehicle 12, for example through OBDII connector 132. Electric vehicle 12 is illustrated as including a plurality of systems identified as System A, B, C through System N. These systems can be any active or passive electrical component or set of components within the vehicle including a motor or motors of the vehicle, an energy recovery system such as a regenerative braking system, a battery cell, a block of cells, a battery pack, vehicle electronics such as audio systems, defrosters, wipers, adjustable seat motors, seat heaters, internal and external lights, computer systems, electrical systems associated with an electric or internal combustion motor, charging systems, or others. Each of the systems A-N is illustrated as having a current sensor 140A-140N, respectively and a voltage sensor 142A-142N, respectively. The multiple current sensors 140 and voltage sensors 142 are provided for illustrative purposes only and a particular system within the vehicle may be have neither type of sensor, may have a single sensor, or may have multiple sensors. The outputs from the current sensors 140 the voltage sensors 142 are provided to the internal databus of the electric vehicle 130. The electric vehicle 12 may include additional sensors for sensing physical properties such as temperature, moisture content, fluid levels, pressures, speed or rate of rotation of motors, flow rate, whether a switch is opened or closed, etc. These sensors are illustrated in FIG. 4 as sensor A, B through sensor N and are also coupled to the databus 130 of electric vehicle 12. The sensors A, B, . . . N may be associated with any of the above discussed systems A-N, or with other components or aspects of the electric vehicle 12. For example, a particular sensor may provide a temperature reading of a particular system, or other measurement related to the system. Note that the coupling of the various sensors to the databus 130 may be direct or indirect. For example, data from a particular sensor may be provided to another component, such as directly to a microprocessor 150 of the electric vehicle. Subsequently, the microprocessor 150 may provide the information on databus 130. The data from the various sensors may be optionally stored in an internal memory 152 of the electric vehicle 12. In FIG. 4, the memory 152 is illustrated as being coupled to microprocessor 150. However, this may be optional and the memory 152 can be coupled to databus 130, either directly or through some other component. In one aspect of the present invention, test device 14 monitors information from sensors within the electric vehicle in order to provide enhanced diagnostics without requiring connection of additional sensors to the electric vehicle 12. This is achieved by retrieving data through the databus 130 of the electric vehicle as the various sensors within the vehicle communicate information.

In measuring electrical parameters of components, it is often desirable to couple to the electrical component through a four point “Kelvin” connection. In such a configuration, a first pair of connections are used to measure a voltage across the component while a second pair of connections are used to carry current. Kelvin connections reduce errors in the measurements associated with the electrical leads and wiring which are used to couple to the component. However, in many electric vehicles, it is extremely difficult to place Kelvin connectors onto the various electrical components. Further, even if such connections are made, they may carry high voltages which may be unsafe for an operator. Therefore, it is often difficult to couple to the electrical systems of an electric vehicle using traditional Kelvin connection techniques which have been associated with the automotive industry.

In one aspect, the present invention provides a “virtual Kelvin” connection to electrical components of the vehicle. The “virtual Kelvin” connection is embodied in microprocessor 33 of the test device 14. Microprocessor 33 receives current and voltage information from a pair of sensors, such as current sensor 140A and voltage sensor 142A, which are coupled to a component of the electric vehicle 12 such as system A. Using this information, the microprocessor 33 is capable of calculating an electrical parameter associated with that particular system. For example, electrical resistance can be calculated using Ohms' law as R=V/I. However, other electrical parameters can be calculated such as conductance. Further still, if the electricity through the system has a time varying component, it is possible to determine dynamic parameters of the system such as dynamic resistance or conductance. Complex parameters such as impedance, reactance, etc. of the particular system can also be determined. Note that there may be a lag or time delay between the two measurements (voltage and current) due to delays in the databus 130 or due to other causes. Microprocessor 33 can compensate for such a lag by determining, or at least approximating, the duration of the delay. One technique which can be used is to monitor a function or activity within the vehicle, for example, a braking function, while monitoring the outputs from the associated current and voltage sensors. Based upon when the current and voltage begin to change relative to one another, it is possible to compensate for any delays if the relationship is known. For example, the voltage and current may be expected to rise simultaneously in some systems. If there is a lag in the voltage measurement, for example, the duration of that lag can be measured by microprocessor 33 and used to compensate subsequent measurements. Similarly, a particular sensor may have a relatively long response time, or the databus 130 may be of a sufficiently slow data rate that sufficient band width may not be available to measure or monitor a rapidly changing voltage or current. Again, compensation techniques can be used to at least partially address such a shortcoming, for example, by providing a compensated frequency response profile for a particular sensor. This information can be used to characterize a particular sensor or measurement performed using a set of sensors. This characterization can compensate for such measurements in use to thereby improve the accuracy of the measurement. The compensation characterization can be determined experimentally and thereby stored in the test device 14, or can be determined empirically by monitoring operation of the vehicle 12 as discussed above. This characterization information can be stored in memory 32 of test device 14 and use to compensate the measured parameters.

During operation, microprocessor 33 collects data from a desired system (A-N) of electric vehicle 12 using the associated current sensor 140A-N and/or voltage sensor 140A-N as desired. The microprocessor 33 can also use information collected from other sensors of the electric vehicle, such as sensors A-N for use in testing as desired. If a measurement is desired across multiple systems, it is possible to add or subtract the measured currents and voltages to obtain such a measurement, depending upon the configuration of the sensors. As discussed above, the data is retrieved from databus 130 using OBDII I/O circuitry 112 coupled to the databus 130 through OBDII connector 132. In addition to having a user input/output 110, another optional input/output (I/O) 160 is illustrated. I/O 160 can comprise circuitry for providing data to, or receiving data from, another device such as a remote location which collects data or measurements, a printer, a remote control or display for use by an operator, remote sensors, etc. Additionally, other optional sensors 162 are shown in test device 14 of FIG. 4. Sensors 162 may comprise other sensors used to perform diagnostics including physical Kelvin connectors, current and/or voltage sensors, temperature sensors, etc. The user I/O circuitry 110 can be used to provide an interface for an operator during testing of electric vehicle 12. For example, the operator can provide information to the test device 14 related to which of the systems of electric vehicle 12 to test, to a selected test to perform, to provide information regarding electric vehicle 12, etc. The I/O circuitry 110 can also be used to provide information to the operator such as the results of a test, intermediary test results, information regarding past tests, information regarding the electric vehicle 12, information regarding the history of the vehicle 12 or other information. Additionally, if a particular test requires the electric vehicle 12 to be operated in a particular manner, the user I/O circuitry 110 can provide instructions to the operator. For example, the particular test being performed may require that the electric vehicle 12 be accelerated, or that the brake be applied, that the electric vehicle be stopped for a period, or other actions. The instructions to an operator may be in the form of, for example, audible or visual instructions which may be easily received when operating the electric vehicle 12. Using the data collected from the sensors, microprocessor 33 can diagnose individual systems and the overall operation of electric vehicle 12. In one example of the present invention, the information can be used to perform any type of diagnostics such as those known in the art. Various types of diagnostics include measuring parameters of systems of the electric vehicle 12, monitoring the amount of energy recovered during an energy regenerative process such as by recovering energy during a braking function, determining the maximum amount of energy which may be recovered, or the maximum amount of energy which the energy storage device can accept at any one time during recharging, monitoring the energy storage device as it ages to identify a loss of the capacity to store recovered energy or the overall capacity of the storage device 20, monitoring the maximum energy which the energy storage device 20 is capable of delivering, etc.

For example, one diagnostic technique includes monitoring a parameter of a cell or block of cells of the battery pack 20 and observing changes over time, for example changes in impedance, conductance, resistance, or other parameters including dynamic parameters. Another example diagnostic includes comparing parameters measured for a particular cell or block of cells of the battery pack 20 and observing any imbalances between cells or blocks of cells, or other indications that a particular cell or block of cells is not operating in a manner which is similar to the remaining cells or blocks of cells. This may be through statistical techniques such as observing the distribution of measurements of cells or blocks of cells, etc. Another example diagnostic technique is simply observing voltage differences across cells or blocks of cells in the battery 20.

In another example, the user I/O 110 is used to provide an output related to carbon dioxide emissions of the electric vehicle 12. For example, the output can be an indication of the reduction in carbon dioxide emissions of the electric vehicle 12 in comparison to a standard vehicle with an internal combustion engine. In a related example, the amount of energy regenerated by electric vehicle 12, for example using a regenerative braking technique, can be monitored using test device 14 and an output provided using user I/O 110 which indicates the equivalent amount of carbon dioxide which would have been generated by typical internal combustion engine had the energy not been recovered.

In another example configuration, test device 14 can be used to monitor operation of electric vehicle 12 and collect information related to the efficiency of the electric vehicle 12 under different operating conditions. This information is then used by device 14 to instruct an operator through user I/O 110 to operate the electric vehicle 12 in a manner which increases efficiency. For example, if system A shown in FIG. 4 comprises a regenerative braking system, and system B is the battery pack 20 for the electric vehicle 12, the test device 14 can be configured to monitor the energy recovered by the regenerative braking system and the amount of energy which the battery pack 20 is capable of storing. Thus, if measurements indicate that the battery pack 20 is only capable of accepting a maximum of 50 kW, the test device 14 can instruct the operator when braking to attempt to rapidly approach the 50 kW energy recovering level, and maintain the 50 kW level for an extended period without exceeding that level. This will ensure that the maximum amount of energy is recovered during a braking operation. Similar techniques can be used to instruct the operator during acceleration periods, idling periods, “stop and go” traffic, etc. In a more advanced configuration, the device 14 is configured to control operation of the systems in vehicle 12 in a manner which differs from the configuration provided by the vehicle control system, for example, as implemented in the microprocessor 150 of electric vehicle 12. For example, the test device 14 can provide instructions or information on databus 130 which allows the charging system or the regeneration system of electric vehicle 12 to charge the battery pack 20 to a higher or lower level than that set by the internal control system of the vehicle. This may be used, for example, to extend the life of systems within the vehicle, increase the range of the vehicle, test certain systems, or for other functions or purposes.

The particular test performed by the test device 14 can be a simple evaluation and indicate and good or bad battery pack 14, or can provide more detailed information such as the total battery pack dynamic conductance or impedance, or a dynamic parameter related to an individual cell or group of cells in the pack 20, etc. During testing, the device 14 can communicate with the operator to instruct the operator to perform a particular operation with the vehicle, such as aggressive acceleration or deceleration. This can be communicated through an audible or visual technique that does not interfere with vehicle operation such as lights, voice prompts, tones or sounds, etc. this may be communicated to the operator using I/O components that are a part of vehicle 12, for example, a vehicle speaker, display, etc. In one configuration, the device 14 instructs the driver to operate the vehicle 12 in a safe manner. If temperature data is available, for example through a temperature sensor, the test measurements can be compensated based upon temperature. If an external PDA or cellular “smart phone” type device is used, the interface with the operator can be provided through such a device. For example, in one configuration, the user I/O such as element 110 shown in FIG. 3, comprises a remote device such as a “smart phone” capable of communicating with an operator. Communication with the “smart phone” can be through wireless communication techniques such as WiFi, Bluetooth, cellular network, etc., or can be through wired techniques such as a data cable or other connection.

The test device 14 can be configured to recognize when certain conditions have been met by monitoring, for example, engine speed (RPM), vehicle miles per hour, vehicle acceleration and deceleration, etc. This can be by using instruments onboard the vehicle 12 such as GPS information, the output from a speedometer, etc. Once a complete data set has been obtained as desired for a particular test, the test device 14 can provide an output accordingly. The test can be modified based upon driving conditions and the duration of the test can be extended as needed. Instructions can be provided to the operator and, in some configurations, the operation of the vehicle 12 can be controlled by the test device 14. For example, gearing or braking of vehicle 12 can be controlled, requesting the vehicle 12 enter “EV” mode, operating certain accessories on the vehicle, monitoring acceleration or braking, monitoring torque provided by vehicle motors, engine parameters such as fuel mix, etc can be monitored or controlled, or other elements controlled or monitored as desired. The operator can be informed that the vehicle 12 is being operated correctly or incorrectly using an audible or visual output. Any “trouble codes” available on the databus of vehicle 12 can also be incorporated into the testing. One type of test involves the vehicle 12 being “blocked”, in other words placed onto a test stand in which the vehicle 12 is operated on rollers. The test device 14 can be configured to operate in such a mode for use in monitoring acceleration and deceleration tests, etc. If the test device 14 is temporarily coupled to the vehicle 12, it can be configured to be left in the vehicle 12 for an extended period while an operator drives the vehicle 12 under normal operating conditions. This allows the vehicle 12 to be monitored during “real life” drive cycles as data is collected. In one configuration, the test device 15 monitors instantaneous fuel usage and combines this fuel usage with a battery test. This information can be useful in identifying bad battery packs or battery within the pack 20 and used to monitor the efficiency of the charging cycle. A poor charging cycle indicates a bad battery and will result in increased fuel usage. The test device 14 can record the fuel usage, the number of starts, or other information and store such information in a flash memory for subsequent recovery.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. For example, although storage batteries or a “battery pack” described, as used herein the term electric energy storage device includes a battery or collection of batteries, capacitors including supercapacitors and ultracapacitors, and other electrical energy storage devices. As used herein, electric vehicle includes any type of vehicle which uses an electric motor to propel, or assist in propelling, the vehicle. One example electric vehicle is a vehicle with an electric motor and an electric storage device such as a battery pack or the like. Another example electric vehicle is an electric vehicle with regenerative techniques in which energy is recovered, for example, from the braking process. Another example electric vehicle is a hybrid vehicle which also includes an internal combustion engine for use in supplementing electric power, and/or charging the electrical energy storage device. Such a hybrid vehicle may optionally include regenerative systems for energy recovery. As used herein, “operating” an electric vehicle includes using the vehicle, or systems of the vehicle, and is not limited to driving the vehicle. In one configuration the test device is separate from the vehicle and may be selectively coupled to the vehicle or added after manufacture of the vehicle. The “virtual” Kelvin configuration can be used to calculate a parameter of a system of the vehicle using two or more inputs from sensors which are transmitted over a databus of the vehicle. 

What is claimed is:
 1. A method of testing an electrical system of an electric vehicle, comprising: operating the electric vehicle; coupling a test device to a databus of the electric vehicle; monitoring data on the databus and retrieving information related to current flowing into a system of the electric vehicle with the test device during the step of operating; monitoring data on the databus and retrieving information from a sensor of the vehicle related to a voltage of the electrical system with the test device during the step of operating; providing instructions to an operator which instruct the operator to operate the electrical vehicle in a specific manner; recognizing when certain conditions have been met with the test device during the step of operating the vehicle; and diagnosing the electric vehicle with the test device based upon the monitored current and the monitored voltage.
 2. The method of claim 1 wherein diagnosing includes comparing monitored current and monitored voltage with nominal values.
 3. The method of claim 1 including wirelessly communicating the retrieved information to a mobile device.
 4. The method of claim 1 wherein the databus comprises an OBDII databus.
 5. The method of claim 1 wherein the system comprises a battery pack of the vehicle.
 6. The method of claim 5 including monitoring a second system of the vehicle.
 7. The method of claim 6 wherein the second system comprises a regenerative braking system of the vehicle.
 8. The method of claim 7 wherein diagnosing comprises monitoring energy output from the regenerative braking system and monitoring energy input into the battery pack.
 9. The method of claim 8 wherein the diagnosing further comprises determining efficiency of a transfer of energy recovered from the regenerative braking system and stored in the battery pack.
 10. The method of claim 1 wherein the system comprises a block of cells of a battery pack of the electric vehicle.
 11. The method of claim 10 including monitoring a second block of at least one or more cells of the battery pack.
 12. The method of claim 11 wherein the diagnosing comprises comparing a parameter of the first block of cells with a parameter of the second block of cells.
 13. The method of claim 1 wherein the diagnosing comprises measuring a parameter of the system.
 14. The method of claim 13 wherein the parameter comprises a dynamic parameter.
 15. The method of claim 1 including providing an output to an operator of the electric vehicle.
 16. The method of claim 15 wherein the output comprises instructions related to operation of the vehicle for use in performing the step of diagnosing.
 17. The method of claim 1 wherein the electric vehicle comprises a hybrid vehicle.
 18. The method of claim 17 wherein the system comprises an electric generator coupled to an internal combustion engine of the electric vehicle.
 19. The method of claim 18 including monitoring a second system of the electric vehicle, wherein the second system comprises a battery pack and the step of diagnosing comprises determining efficiency of storage of energy from the generator by the battery pack.
 20. The method of claim 1 wherein the diagnosing includes compensating for a difference between retrieving information related to current flowing into the system and retrieving information related to the voltage of the system.
 21. The method of claim 1 including placing information onto the databus which affects operation of the electric vehicle.
 22. The method of claim 1 including placing information onto the databus which affects operation of a system of the electric vehicle.
 23. The method of claim 1 including providing an output to an operator of the vehicle to instruct the operator to operate the vehicle in a manner to increase energy efficiency of the vehicle.
 24. An apparatus for testing an electric vehicle, comprising: a databus connector configured to connect to a databus of the electric vehicle; a microprocessor configured to: retrieve voltage information from the databus of the electric vehicle provided by a voltage sensor of the vehicle coupled to an electrical system of the electric vehicle; retrieve current information from the databus of the electric vehicle provided by a current sensor of the vehicle coupled to the electrical system of the electric vehicle; instruct an operator to operate the electrical vehicle in a specified manner; recognize when certain conditions have been met during the step of operating by monitoring the vehicle; and diagnose the operation of the vehicle based upon the retrieved current information and the retrieved voltage information.
 25. The apparatus of claim 24 wherein the microprocessor compares monitored current and monitored voltage or a function of monitored voltage and monitored current, with nominal values.
 26. The apparatus of claim 24 wherein the databus comprises an OBDII databus.
 27. The apparatus of claim 24 wherein the system comprises a battery pack of the vehicle.
 28. The apparatus of claim 27 wherein the microprocessor monitors a second system of the vehicle.
 29. The apparatus of claim 28 wherein the second system comprises a regenerative braking system.
 30. The apparatus of claim 29 wherein the microprocessor monitors energy output from the regenerative braking system and monitors energy input into the battery pack.
 31. The apparatus of claim 30 wherein the microprocessor further determines efficiency of the transfer of energy recovered from the regenerative braking system and stored in the battery pack.
 32. The apparatus of claim 24 wherein the system comprises a block of one or more cells of a battery pack of the electric vehicle.
 33. The apparatus of claim 32 wherein the microprocessor monitors a second block of one or more cells of the battery pack.
 34. The apparatus of claim 33 wherein the microprocessor compares a parameter of the first block of cells with a parameter of the second block of cells.
 35. The apparatus of claim 24 wherein the microprocessor measures a parameter of the system.
 36. The apparatus of claim 35 wherein the parameter comprises a dynamic parameter.
 37. The apparatus of claim 24 including an output provided to an operator of the electric vehicle.
 38. The apparatus of claim 24 wherein the electric vehicle comprises a hybrid vehicle.
 39. The apparatus of claim 24 wherein the system comprises an electric generator coupled to an internal combustion engine of the electric vehicle.
 40. The apparatus of claim 39 wherein the microprocessor monitors a second system of the electric vehicle, wherein the second system comprises a battery pack and the microprocessor determines efficiency of storage of energy from the generator by the battery pack.
 41. The apparatus of claim 24 wherein the microprocessor compensates for a difference between retrieving information related to current flowing into the system and retrieving information related to a voltage of the system.
 42. The apparatus of claim 24 wherein the microprocessor is configured to place information onto the databus which affects operation of the electric vehicle. 